Sensory eartips for measuring an individual's response to auditory stimuli are known in the art. For example, U.S. Pat. No. 4,622,975 dated Nov. 18, 1986 describes an earcanal electrode utilizing a tubular electrode of conductive material having an end area surrounded by plastic foam which is impregnated with a conductive gel for sensing electrical stimuli from the skin of the earcanal that results from the audio stimulus through a sound channel within the electrode. The description of the prior devices and the environment for the apparatus described in the '975 patent is incorporated herein by reference and forms a part of the present disclosure. Eartips of the general type shown in U.S. Pat. No. 4,622,975 are also made by Avonics Instruments of Mountain View, Calif.
Eartips of the foregoing general type have had certain inherent disadvantages. The gels that impregnate the foam generally dry out in normal atmospheric conditions, necessitating the use of expensive, air impervious packaging. Once the integrity of the packaging is compromised, rapid deterioration can be expected. Provision of a separate gel container complicates the use of the eartips by the operator of the diagnostic equipment. Additionally, the use of a metal conductor deep in the earcanal involves inherent risks of injury to the sensitive membranes of the ear by a careless or incompetent diagnostician.